Video signals are requiring a high amount of bandwidth to be transmitted and recorded, more particularly with digital transmission schemes. Most of the bandwidth and memory requirements, in the internet, are dedicated to video, and as a result, frequent limitations or losses of image quality appear.
Digital compression systems require a high bit count (equivalent to large bandwidth) to process a scan video signal with an acceptable quality. The requirements for bandwidth are increasing daily, and the available bandwidth provided by present communication channels is limited. For example, more than 50% of Internet traffic is occupied by video.
Broadcasters are no longer satisfied with present HDTV standards (1080i and 720p) and would like to move to higher scan rates (e.g., “4K”, which is approximately 2000×4000 pixels) or higher frame rates (120 Hz). Furthermore, interlace standards, which in the past employed analog transmission, reduced the bandwidth requirements by two at the cost of image quality (artifacts). Interlacing does not present such an advantage in compression systems, and is not computer-friendly.
Thus, increased bandwidth is required. As an alternative, a more efficient use of the existing bandwidth is preferable.
Compression standards are slowly improving, getting more efficient in packing an increasing data load into increasingly over-worked channels, but an improvement by a ratio of two in the bandwidth utilization (Mb/s for a constant channel) occurs only every eight to ten years or so.
Furthermore, conventional video compression systems tend to focus on mathematical comparisons of video inputs and video outputs before and after compression, rather than focusing on the visible quality of the video data in bit-rate reduction attempts. Consequently, conventional video compression systems are not typically optimized for retaining visible video quality of the video data relative to bit-rate reductions.
A need has arisen, therefore, to reduce the bandwidth, or Mbits/sec, of digitally compressed video signals, while maintaining a reasonable image quality after decoding.